中文摘要：

以太湖流域肖甸湖区为代表,测定分析了肖甸湖围湖造田区香樟林、水杉林、毛竹林、农田4种典型的不同土地利用方式0～40cm土层水溶性有机碳含量的差异及其季节动态。结果表明：不同土地利用方式对土壤水溶性有机碳含量影响显著,并且在不同土层表现不同。0～10cm土层农田中的水溶性有机碳含量比3种林地的小,针叶林中的比阔叶林的大;而10～20cm与20～40cm土层水溶性有机碳含量变化与之相反。土壤水溶性有机碳含量在垂直方向上具有明显的分层现象,林地土壤自上而下呈下降趋势;除12月冬闲期外,农田各土层土壤水溶性有机碳含量的垂直变化由大到小依次为10～20、20～40、0～10cm。不同土地利用方式土壤水溶性有机碳含量均表现出明显的季节动态,总体表现为秋冬季节大于春夏季节。与旱地发育的植被土壤相比,围湖后的土壤水溶性有机碳含量较高,土壤有机碳稳定性较差;与干湿交替的平原湿地相比,围湖后的土壤水溶性有机碳含量较低,土壤有机碳稳定性较强。围湖造田作为人类对自然生态系统的一种干扰方式,显著改变了原有生态系统的碳循环,因此应该充分考虑围湖造田对生态系统碳循环的影响。

英文摘要：

Reclaimed land from a lake area is a kind of human disturbance that has emerged in large numbers since the late 1950s in China.In order to understand the characteristics of soil water soluble organic carbon （WSOC） in the reclaiming land from lake under different land uses in the Xiaodian Lake area,the concentrations and seasonal dynamics of WSOC in the 0—40 cm soil layer were analyzed.The results showed that the effects of land uses on WSOC concentrations were significant.The concentrations of WSOC under cropland were lower than those in forests at 0—10 cm deep of soil layer,and the concentrations under coniferous forest were higher than those in broadleaf forest.At 10—20 cm and 20—40 cm deep of soil layer the WSOC concentrations under cropland were higher than those in forests,and the concentrations under coniferous forest were lower than those in broadleaf forest.The concentrations of WSOC under each forest land decreased sharply with increasing soil depth.Except for December,the vertical change of WSOC concentrations in cropland soil was different from forests：the highest concentrations were at 10—20 cm depth while the lowest were at 0— 10 cm depth.Seasonal dynamics of WSOC under each land use were significantly.The concentrations of WSOC in autumn and winter were higher than those in spring and summer,generally.WSOC concentrations in the impoldering land were higher relative to the upland of the same climate zone and lower compared with other wetland,indicating that the stability of WSOC in the impoldering land was lower than that in the upland and higher than that in the wetland with the alternation of wetting-drying.Thus it is important to note the effect of reclaiming land from a lake on the carbon cycle in terms of global climate change.